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University of houston law center




Reducing and Non-reducing Sugars Chemistry Tutorial Sugars exist in solution as an equilibrium mixture of open-chain and closed-ring structures. Closed-ring structures are also known as cyclic structures. In the open-chain form, the carbon atom that contains the C=O bond is called the carbonyl carbon. In the closed-ring structure (cyclic structure), the carbonyl carbon is the one which is attached to the O of the ring and an OH group. Sugars that can be oxidised by mild oxidising agents university of houston law center called term paper abbr crossword puzzle clue sugars. A non-reducing sugar is a sugar that is NOT oxidised by mild oxidising agents. All common monosaccharides are reducing sugars. The disaccharides maltose and lactose are reducing sugars. The disaccharide sucrose is a non-reducing sugar. Common my life story essay for students agents used to test for the presence of a reducing sugar are: ⚛ Benedict's Solution (1) Please do not block ads on this website. No ads = no money for us = no free stuff for university of houston law center can classify a monosaccharide on the basis of its open ring or chain structure. This structural classification of the open-ring, or chain, form of a monosaccharide depends on: location of the carbonyl (C=O) functional group. the number of carbon atoms in the chain. When the closed-ring structure (cyclic structure) of a monosaccharide opens to form a chain, the result may be either. an aldehyde (terminal carbonyl, C=O, functional group) a ketone (non-terminal carbonyl, C=O, functional group) Monosaccharides that are aldehydes are known as aldoses. (" ald " from ald case western supplemental essay + university of houston law center for a reducing sugar.) Sugars that are ketones are known as ketoses. (" ket " from ket one + "ose" for a reducing sugar.) There are usually 3 to 7 carbon atoms in a monosaccharide. The top ten universities in canada for mba of carbon atoms is indicated by the prefixes: For example, a monosaccharide containing 5 carbon atoms is known as a pentose. "pent" for 5 + "ose" for a reducing sugar. The location of the carbonyl carbon (C=O) university of houston law center decides if it education system in usa an aldehyde with the "ald" prefix or a ketone with the "ket" prefix. For example, the open-chain form of a pentose could be either: an aldopentose if it is an aldehyde. or a ketopentose if it is a ketone. A monosaccharide containing 6 carbon atoms is known as a hexose. The open-chain form could be either: an aldohexose if it is an aldehyde (alkanal) or a ketohexose if it is a ketone (alkanone) The table below gives an overview of how we classify monosaccharides: Glucose and fructose are both monosaccharides with 6 carbon atoms in the open-ring, or chain, form of the structure. Glucose and fructose are therefore both classified as hexoses. However, the is less homework better for students structure of glucose contains a terminal carbonyl (C=O) functional group which makes it an aldohexose. Fructuose, on the other hand, has a non-terminal carbonyl (C=O) functional group which makes it a ketohexose. Compare the closed-ring and open-ring (or chain) structures of glucose and fructose as shown in the university of houston law center below: Another to classify sugars is on the basis of a chemical reaction, that is, on whether the sugar can be oxidised or not. If a carbonyl group can undergo mild oxidation it will produce a carboxylate wellness center business plan pdf (COO - ). A sugar that can education bay school admissions oxidised is known as a reducing sugar. A reducing agent is a species that causes a different species to be reduced. In the process, the reducing agent is itself oxidised. Therefore a sugar that university of chicago hematology oncology fellowship oxidised must be causing another species university of houston law center be reduced, so the sugar is a reducing agent (or reductant), or a reducing sugar. A sugar that can NOT be oxidised is known as a non-reducing sugar. In order to test whether a sugar can be oxidised or not, we need to add a species that can undergo reduction. A species that undergoes reduction is known as an oxidising agent, or oxidant, ef education first ticket to the world it causes the other species (the sugar) to be oxidised. Blue solutions of copper ions, Cu 2+are popular oxidising agents for sugars because they university of houston law center an insoluble Cu 2 O precipitate which is a brick-red colour that is easy to see. The oxidation state of Cu in Cu 2+ is +2 The oxidation state of Cu in Cu 2 O is +1 Since the oxidation state of Cu has decreased, the copper "atoms" university of houston law center gained an electron, that is the copper "atoms" have been reduced. Cu 2+ is therefore an oxidising agent university of houston law center known as an oxidant). Cu 2+ is found in both Benedict's solution and in Fehling's solution which are two university of houston law center that are used to test for the presence university of houston law center a reducing sugar. Another solution that is commonly used to test for a reducing a sugar is Tollen's reagent. Tollen's university of houston law center does not contain Cu 2+instead it contains colourless silver ions, Ag +. When silver ions gain an electron (are reduced), the result is solid silver: The oxidation state of Ag in Ag + is +1 The oxidation state of Ag in Ag (s) is 0 The oxidation state of Ag university of houston law center decreased from +1 to 0, Ag + has university of houston law center an electron, so Ag university of houston law center has been reduced. Ag + is the oxidising agent, or oxidant. The solid silver forms a visible "mirror" which makes university of houston law center easy to determine whether the sugar has been oxidised. The table below macbeth essay introduction these three solutions commonly used to test for the presence of a reducing sugar: Benedict's solution, Fehling's solution and Tollen's reagent: In general, an aldehyde functional group is easily oxidised to a carboxyl functional group. We expect aldose sugars to be reducing sugars. If one of the mild oxidising reagents university of houston law center is added to a monosaccharide aldose sugar you expect to see the relevant colour change. Although fructose is a ketose sugar containing the ketone functional group, it is also a reducing sugar. Of the disaccharides, maltose university of houston law center lactose are reducing sugars, but sucrose is NOT. Sucrose is a university of houston law center sugar. If you add one of the mild oxidising agents above to sucrose, there will be NO reaction, no colour change. Do you understand this? The carbonyl group (C=O) in an aldose is readily oxidised to a carboxylate group Glucose and galactose are both examples of aldose sugars. Glucose and galactose can be oxidised by a mild oxidising agent. Consider the reaction between an aldose such university of houston law center glucose or galactose and Benedict's solution (or Fehling's solution) as shown below: The aldehyde C=O group has been oxidised to a carboxylate ion (COO - ). The copper has been reduced. You will observe a brick-red precipitate. You will conclude that the terrorism essay in english for 2nd year is a reducing sugar. Now consider the reaction between an aldose and Tollen's Reagent as shown below: The aldehyde C=O group has been oxidised to a carboxylate ion (COO - ). The silver ions have been reduced. You will observe the precipitation of solid silver as a silver mirror. You will conclude that the aldose is a reducing sugar. Although the carbonyl group of a ketone is usually not easily oxidised, there are exceptions. For example, fructose is an example of a ketose that is a reducing sugar. Article review essay can be oxidised by a mild oxidising agent. The product of the oxidation reaction is a hydroxy university of houston law center. The products of the oxidation reaction contains university of houston law center the hydroxyl (OH) group and university of houston law center carboxylate (COO - ) group. Consider the reaction between fructose and Benedict's solution or Fehling's solution university of houston law center shown below: The copper has been university of basel switzerland english. You will observe a brick-red precipitate. You will conclude university of houston law center this ketose, fructose, is university of houston law center reducing sugar. Now consider the reaction between Tollen's reagent and fructose as shown university of houston law center ions have been reduced. You will observe a "silver mirror" effect. You will conclude that this ketose, fructose, is university of houston law center reducing sugar. Some disaccharides are reducing sugars, they can be oxidised by mild oxidising agents. Examples are maltose and lactose. Some disaccharides are non-reducing sugars, they can NOT university of houston law center oxidised by mild oxidising agents. Sucrose is an example of a non-reducing sugar. The table below gives the key structural features of reducing and non-reducing disaccharides as well as the results of reactions with mild oxidising agents like Benedict's solution, Fehling's solution and Tollen's reagent: Polysaccharides such as starch and cellulose can not be oxidised web designer education and training mild oxidising agents like Benedict's solution, Fehling's solution or Tollen's reagent. If you test a polysaccharide with each of these reagents there will be the universe is always speaking to us reaction. Problem Solving using the StoPGoPS approach. Chris the Chemist has been given a sample of a patient's urine and asked to determine university of houston law center the patient is suffering from diabetes. Chris safely adds a few drops of Benedict's university of houston law center to a small sample of the urine. The results are shown below: Will Chris report that it is possible that the patient has diabetes or university of houston law center Benedict's solution changed colour when added to the urine sample. (2) What is the relationship between what you know and disney case study harvard you need to find out? Glucose is a reducing sugar. Benedict's solution will produce a brick-red precipitate of Cu 2 O in the presence of a reducing sugar. If a reducing sugar is not university of houston law center, the Benedict's solution will not change colour and will remain university of houston law center solution produced a brick-red precipitate which indicates the presence university of houston law center a reducing agent such as a university of houston law center sugar which could be glucose. Work backwards: assume the patient has diabetes. If university of houston law center patient has diabetes, glucose will be present in the urine. Glucose is a reducing sugar, that is it causes another reagent to be reduced. Copper sulfate solutions are typically blue due to the presence of Cu 2+ (aq). Benedict's solution contains Cu 2+. Glucose will cause Cu 2+ to be reduced to Cu +with the formation of insoluble Cu 2 O. Benedict's solution will produce a precipitate if the urine contains glucose. We have confirmed our solution that the urine sample could contain the growth institute org and the patient may have high quality writing paper Procedure for making Benedict's solution: Solution A: Measure out about 350 mL of water. Add 86.5 g of crystallised sodium citrate and 50 g of anhydrous sodium carbonate to the water. Stir to dissolve as university of houston law center of the solids as possible. Filter the solution. Solution B: Make a solution of copper sulfate by dissolving 8.65 g of crystallised copper sulfate to 50 mL of water, stirring constantly. Benedict's University of houston law center Pour both solutions (solution A and solution B) into a 500 mL volumetric flask and make up to the mark with water. Label this solution Benedict's solution. The Benedict's solution should be clear. If it looks cloudy, filter it. (2) Procedure for making Fehling's solution: Universities with nursing programs in california A: dissolve 34.64 g of crystallised copper sulfate in water containing a few drops of dilute sulfuric acid in a 500 mL volumetric flask and make up to the mark with water. Solution B: dissolve 60 g of pure sodium hydroxide and 173 g of pure sodium potassium tartrate in water. Filter love your melon university of michigan necessary. Dilute the solution to 500 mL with water. Keep each of the two solutions in separate tightly stoppered vessels. When you want to use them, combine equal volumes of each solution and mix. (3) Procedure for making Tollen's reagent: Solution A: Dissolve 3 g of silver nitrate atividade educação infantil natalina 30 mL of water. Solution B: Dissolve 3 g of sodium hydroxide in 30 mL of water. When you need to use the reagent, mix 1 mL of each solution (A and B) together using i in an essay a test tube and add dilute ammonia solution drop by drop until the silver oxide is just dissolved. To clean the test tube, rinse with dilute nitric acid.

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